The future wireless communications systems should be able to offer wide variety of applications, which have vastly different quality of service (QoS) requirements. The time-variable QoS may require the support of variable bit rates on the wireless links to the individual users. Multi-rate DS/CDMA is a promising basis on which to support the variable bit rates on the individual wireless links. C...

Orthogonal Frequency Division Multiplexing (OFDM) has become a very popular method for high data rate wireless communications because of its advantages over single carrier modulation schemes on multi-path, frequency selective fading channels. However, inter-carrier interference due to Doppler frequency shifts, and multipath fading severely degrades the performance of OFDM systems. Estimation of...

Orthogonal Frequency Division Multiplexing (OFDM) has become a very popular method for high data rate wireless communications because of its advantages over single carrier modulation schemes on multi-path, frequency selective fading channels. However, inter-carrier interference due to Doppler frequency shifts, and multipath fading severely degrades the performance of OFDM systems. Estimation of...

We design pilot symbol assisted modulation for carrier frequency offset (CFO) and channel estimation in orthogonal frequency division multiplexing (OFDM) transmissions over multi-input multi-output (MIMO) frequency-selective fading channels. By separating CFO and channel estimation from symbol detection, the novel training patterns lead to low-complexity CFO and channel estimators. The performa...

A Generalized Frequency Hopping (GFH) OFDMA system is developed in this paper as a structured long code DS-CDMA system in order to bridge frequency hopped multi-carrier transmissions with long code DS-CDMA. Through judicious code design, multiuser interference is eliminated deterministically in the presence of unknown frequency-selective multipath channels. Thanks to frequency hopping, no singl...

-In this paper, we propose iterative soft-input soft-output (SISO) multi-carrier detection (inter-carrier interference cancellation) and LDPC decoding of the OFDM system in the mobile channel. The proposed SISO multi-carrier detection and sum-product decoding of the LDPC-coded OFDM system can achieve better error rate performance than previous SISO multi-carrier detection and BCJR decoding of c...

In this paper, we investigate preamble designs for channel estimation, that jointly address the estimation efficiency in terms of mean squared error (MSE) of the channel estimates, and the out of band (OOB) radiation of the transmit preambles. We provide two novel design techniques, based on a convex optimization problem, to obtain optimal preambles for a single carrier and provide a juxtaposit...

Due to the channel with characteristic of sparse multi-path in the 60GHz wireless communication system, the channel estimation problem can be attributed to that of sparse signals recovery. And with the consideration of the subspace pursuit (SP) algorithm is superior to the orthogonal matching pursuit (OMP) at reconstruction precision, the channel estimation technique based on the SP algorithm i...

Abstract In multiple-input multiple-output (MIMO) multiplexing, a superposition of data blocks transmitted from different transmit antennas using the same carrier frequency is received. In a frequency-selective channel, joint use of frequency-domain equalization (FDE) and signal detection of parallel transmitted signals is essential. Recently, we proposed an iterative frequency-domain interfere...

We propose a downlink multiple-input multiple-output multi-carrier code division multiple access system with adaptive beamforming algorithm for smart antennas. The algorithm used in this paper is based on the least mean square, with pilot channel estimation and the zero forcing equalizer in the receiver, requiring reference signal and no knowledge channel. multi-carrier code division multiple a...